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Anna: Hey there, space enthusiasts. Welcome to

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Astronomy Daily, your source for the latest

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news from the cosmos. I'm Anna.

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Avery: And I'm, um, Avery. We've got another packed

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show today with some fascinating storeys from

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both near and far. Anna, uh, what are we

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covering?

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Anna: Well, Avery, we're starting close to home

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with some breaking news from the

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International Space Station. Four astronauts

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just completed the first ever medical

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evacuation from the ISS and

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splashed down safely back on Earth.

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Avery: That's quite significant. We'll also be

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diving, diving into a cosmic mystery about

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missing galaxies. Getting an update on

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NASA's troubled MAVEN spacecraft orbiting

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Mars, and exploring some surprising findings

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about how viruses behave in microgravity.

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Anna: Plus, we'll discuss two newly discovered

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exoplanets that are challenging how we think

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about habitable zones. And we'll wrap up with

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an absolutely stunning new radio image of

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the Milky Way that's revealing hidden

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structures we've never seen before.

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Avery: Lots to get through, so let's jump right in.

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Anna: Alright, Avery, start with Our top storey.

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4 International Space Station crew members

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successfully splashed down in the Pacific

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Ocean off the coast of San Diego early this

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morning, marking a historic first for the

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orbital laboratory.

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Avery: Yeah. This was the ISS's first ever

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medical evacuation in its 26 years of

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continuous operation. The crew members

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included American astronauts Mike Fink and

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Zina Cardman, Russian cosmonaut Oleg

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Plutonov and Japanese astronaut Kimiya

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Yui.

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Anna: The capsule touched down at 12:41 Eastern

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Time after spending five months in space.

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Now, NASA has been pretty tight lipped about

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the specific medical issue that prompted this

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early return, which is understandable given

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privacy concerns.

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Avery: Right. What they have said is that the

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affected crew member was and continues to be

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in stable condition. Mike Fink, who was the

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pilot for SpaceX Crew 11, posted on

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social media earlier this week, reassuring

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everyone that the crew is okay and that this

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was a deliberate decision to allow proper

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medical evaluations on the ground. Where full

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diagnostic capabilities exist, that makes

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sense.

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Anna: James Polk, NASA's chief health and Medical

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Officer, mentioned there was a lingering risk

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and uncertainty about the diagnosis that led

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to the decision to bring the crew back

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earlier than originally scheduled. They were

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supposed to stay until mid February.

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Avery: It's worth noting that three other crew

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members remained on the iss. American

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astronaut Chris Williams and Russian

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cosmonauts Sergey Kud Sverchkov and Sergey

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Mikhashev arrived, uh, at the State Station

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in November aboard a Russian Soyuz

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spacecraft. So station operations continue

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normally.

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Anna: This really highlights the importance of

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having trained medical protocols in place.

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The evacuated crew members had been trained

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to handle unexpected medical situations. And

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according to senior NASA official Amit

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Kshatriya, they handled everything extremely

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well.

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Avery: Absolutely. And this serves as a good

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reminder that despite all the incredible

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engineering and planning that goes into

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spaceflight, we're still dealing with human

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bodies. In an extreme environment, things

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can and do happen.

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Anna: Well, we're glad everyone is safe and

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receiving the care they need back on Earth.

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Avery: Alright, Anna.

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Our next storey takes us much further out

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into space and much further back in time.

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For years, astronomers have assumed that if

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they looked hard enough into the deep cosmos,

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they'd find an almost infinite supply of

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tiny, dim galaxies hiding in the darkness.

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Anna: Right. The prevailing theory has been that

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the smaller the galaxy, the more of them

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there should be. It's kind of like a pyramid

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where you have a few massive galaxies at the

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top and exponentially more small ones as you

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go down.

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Avery: Exactly. But a new study led by Xu

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Heng Ma from the University of Wisconsin is

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challenging that assumption. Using data from

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the James Webb Space Telescope's Uncover

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programme, the team looked through a massive

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galaxy cluster called Abel 2744,

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which acts as a natural gravitational lens.

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Anna: Oh, that's clever. The gravity from this

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cluster literally warps space time and acts

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like a cosmic magnifying glass, right?

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Avery: Precisely. It bends and brightens light from

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more distant objects, allowing us to see

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galaxies from the epoch of reionization,

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roughly 12 to 13 billion years ago.

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This was a transformative era, when the first

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stars and galaxies were flooding the universe

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with ultraviolet light.

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Anna: So what did they find that was so surprising?

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Avery: Well, when researchers count galaxies of

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different brightnesses, they normally use

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what's called a luminosity function. It's

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basically a cosmic bar chart showing how many

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bright versus dim galaxies exist. And

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for study after study, the chart kept going

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in one direction. More small think

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galaxies than bigger, brighter ones.

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Anna: But that's not what they found this time.

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Avery: Nope. Instead of continuing to climb, the

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numbers peaked and then started to drop off.

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They're calling this faint end suppression,

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which means that below a certain brightness,

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the population of galaxies actually starts to

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thin out.

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Anna: So where did all these tiny galaxies go?

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Did they just disappear?

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Avery: In a sense, yes. The study suggests it's a

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case of cosmic bullying. In the early

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universe, the intense radiation from the

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first big stars could have heated up the

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surrounding gas so much that small,

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low mass galaxies couldn't hold onto it.

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Without gas, they couldn't form new stars.

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And without stars, they stayed dark,

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essentially becoming cosmic ghosts.

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Anna: That's fascinating, but it also creates a

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problem, doesn't it? I thought these tiny

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galaxies were supposed to be the main drivers

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of reionization.

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Avery: You're absolutely right. This finding

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suggests we might need to rethink our models.

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If these ultra faint galaxies are missing,

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they can't be the ones doing all the heavy

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lifting during reionization. We might need to

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look at slightly bigger, more established

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galaxies to explain how the universe became

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transparent.

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Anna: This is why I love space science. Every

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answer creates 10 new questions.

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Avery: Couldn't agree more. And they'll need more

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data from JWST in upcoming surveys to

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see if this is a universal pattern or just a

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quirk of this particular region of space.

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Anna: Okay, Avery, let's head to Mars now for an

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update on NASA's MAVN spacecraft.

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And unfortunately, it's not good news.

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Avery: No, it's not. NASA officials are now

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saying it's very unlikely they'll be able to

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recover the Mars Atmosphere and Volatile

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Evolution orbiter, which has been silenced

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since December 6th.

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Anna: Maven has been orbiting Mars since September

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2014, studying the planet's upper

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atmosphere and how solar wind strips it away.

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It's also served as a crucial communications

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relay between Mars rovers and Earth.

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Avery: Right. The spacecraft was supposed to pass

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behind Mars as seen from Earth, A routine

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occurrence. But when it emerged, NASA's Deep

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Space Network didn't observe any signal. That

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was over a month ago now.

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Anna: And the telemetry they did manage to recover

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from December 6th wasn't encouraging, was it?

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Avery: Not at all. Analysis of a brief fragment

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of tracking data From a radio science

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experiment indicated the spacecraft was

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tumbling and no longer in its planned orbit.

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That's a really bad sign, because if the

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spacecraft is tumbling, Its antennas aren't

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pointing toward Earth, which makes

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communication basically impossible.

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Anna: They even tried using the Curiosity rover's

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camera to take pictures of MAVEN as it passed

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overhead, assuming it was still in its

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expected orbit. But they didn't detect it.

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Avery: Yeah, on December 16th and 20th.

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The fact that they couldn't spot it suggests

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its orbit has indeed changed significantly.

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Louise Proctor, director of NASA's Planetary

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Science Division, Said it plainly during a

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meeting earlier this week. We will start

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looking again, but at this point, it's

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looking very unlikely that we are going to be

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able to recover the spacecraft.

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Anna: The timing has been particularly challenging,

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too, hasn't it?

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Avery: Absolutely. Mars went into solar

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conjunction on December 29, which is when

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Mars and Earth are on opposite sides of the

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sun. During this period, the sun

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interferes with radio communications, so NASA

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paused all communications with Mars missions.

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That blackout period just ended on January

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16th. So they can resume attempts, but the

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outlook is grim.

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Anna: Um, the good news is that Maven isn't the

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only communications relay at Mars, right?

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Avery: That's correct. Proctor mentioned that other

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orbiters like Mars Reconnaissance Orbiter and

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Mars Odyssey can pick up the slack. She said

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Maven was not a major part of the Mars relay

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network and they're taking steps to ensure

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they can still retrieve data from rovers on

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the surface.

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Anna: Dill, it's sad to potentially lose a

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spacecraft that's been so productive for over

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a decade.

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Avery: Definitely. Maven has made groundbreaking

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discoveries about Mars atmospheric loss and

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even observed an interstellar object called

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3i ATLS late last year.

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Its contributions to planetary science have

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been immense.

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Anna: Our next storey is taking us back to the

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International Space Station, but this time

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we're looking at some much smaller

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inhabitants. Bacteria and the viruses that

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infect them.

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Avery: Oh, this is fascinating research. A new

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study from the University of Wisconsin,

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Madison used E. Coli bacteria and a

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virus called bacteriophage T7

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to study how microgravity affects the

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evolutionary relationship between viruses and

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their hosts.

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Anna: Though they sent bacteria and viruses to

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space.

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Avery: Exactly. They prepared parallel sets of E.

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Coli cultures infected with T7. One

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set stayed on Earth as a control and the

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other went to the ISS to experience

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microgravity. Then they compared what

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happened to both.

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Anna: Groups and I'm, um, guessing things didn't

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play out the same way in both environments.

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Avery: You guessed right. The analysis showed that

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T7 infection still occurred on the ISS,

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but it only proceeded after an initial delay.

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So spaceflight appears to slow down the early

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stages of virus host encounters without

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completely blocking infection.

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Anna: That's interesting on its own, but I imagine

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they dug deeper.

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Avery: They did. They performed whole genome

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sequencing and found that both the viruses

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and bacteria accumulated distinctive patterns

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of mutations in space compared to their

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counterparts on Earth. The viruses evolved

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specific changes that appear to improve their

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ability to bind to and infect bacterial

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cells.

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Anna: And what about the bacteria? Were they just

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sitting drugs?

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Avery: Not at all. The space flown E. Coli

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populations acquired mutations that may

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strengthen their defences against virus

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attack and enhance their chances of surviving

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in near weightless conditions. It's like they

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were engaged in an evolutionary arms race,

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but the rules of the race were different in

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space.

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Anna: So microgravity is actually changing

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how evolution works?

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Avery: In a sense, yes. The study shows that

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spaceflight not only changes the physiology

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of microbes, but also the physical

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environment in which viruses and bacteria

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encounter each other. This alters the rules

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of their evolutionary interaction.

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Anna: Okay, but beyond the pure science

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fascination, does this have any practical

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applications?

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Avery: Absolutely. Here's where it gets really

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cool. They conducted follow up experiments on

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Earth and found that the microgravity

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associated mutations actually increase

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the virus's activity against disease causing

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E. Coli strains that normally resist

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T7 strains that are implicated in

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urinary tract infections and are often drug

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resistant.

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Anna: So by studying viral evolution in space, we

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might actually discover new ways to fight

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antibiotic resistant bacteria here on Earth.

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Avery: That's exactly what the researchers are

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suggesting. According to the authors, these

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space adapted viruses can be harnessed to

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engineer improved bacteriophages for use in

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human health applications.

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Anna: That's incredible. The International Space

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Station continues to prove its worth as a

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unique research platform.

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Avery: Will do for a little while yet.

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Anna: Alright, Avery, let's travel to some distant

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star systems.

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Now, astronomers have discovered two

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new exoplanets that are prompting scientists

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to rethink how we define habitable zones.

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Avery: Yeah, this is really interesting work. The

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research introduces the concept of a

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temperate zone, which is broader than the

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traditional habitable zone we usually talk

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about.

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Anna: Can you explain the difference? I think a lot

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of people assume habitable zone and

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temperate, um, mean the same thing.

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Avery: Good question. The traditional habitable zone

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is pretty narrowly defined. It's the distance

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range from a star where liquid water could

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exist on a planet's surface. But this new

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research led by Madison Scott from the

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University of Birmingham and Georgina

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Dransfield from the University of Oxford,

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expands that to include what they call the

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temperate zone.

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Anna: And how is that defined?

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Avery: The temperate zone is defined by something

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called insolation flux, which describes the

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amount of solar energy reaching a planet's

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surface. They're using a range between about

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136 watts per square metre and

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6805 watts per square metre.

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Earth receives about

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1,361 watts per square metre.

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Just for reference.

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Anna: So it's much broader than the conservative

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habitable zone.

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Avery: Exactly. The point is to identify planets

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that receive moderate levels of stellar

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radiation. They might not be perfect for life

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as we know it, but they're worth studying

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because as our understanding of habitability

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evolves, some of these planets might turn out

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to be more interesting than we initially

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thought.

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Anna: So, uh, what are these two new planets?

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Avery: The first is TOI 6716

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b, which is roughly Earth, sized between

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0.91 and 1.05

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Earth radii and most likely rocky.

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The second is TOI 7384

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b, which is a sub Neptune measuring

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about 3.37 to

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3.77 Earth radi. This one

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probably has a rocky core with a thick

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hydrogen and helium envelope.

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Anna: And they're both orbiting red dwarf

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stars.

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Avery: Correct. They're orbiting what are called mid

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to late type M dwarfs, which are small, dim,

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cool stars. These types of stars are really

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important for this kind of research because

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temperate planets orbiting them are much more

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likely to transit in front of their stars

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from our point of view, making them easier to

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detect and study.

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Anna: So the goal is to build up a catalogue of

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planets that we can actually study in detail.

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Avery: Exactly.

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TOI6716B has a

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predicted transmission spectroscopy metric

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similar to the famous Trappist 1 planets,

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which makes it a good candidate for JWST

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observations if it has retained its

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atmosphere. The researchers conclude that

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these discoveries show the power of combining

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test data with ground based observations to

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build a catalogue of temperate planets for

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atmospheric studies in the coming decade.

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Anna: It's exciting to think we're moving beyond

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just counting exoplanets to actually being

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able to study their atmospheres in detail.

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Avery: And for our final storey today, we're coming

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back home to our own galaxy.

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Astronomers in Australia have just released

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the most detailed low frequency radio image

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of the Milky Way ever produced.

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Anna: This image is absolutely stunning.

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It was captured by the Murchison Wildfield

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Telescope in Western Australia and reveals

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thousands of structures across the galaxy's

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southern sky that we've never seen in this

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kind of detail before.

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Avery: And the numbers behind this are pretty

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impressive. It took over 1 million CPU

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hours to process the data, which was

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collected across 141 nights between

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2013 and 2020.

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Anna: And this isn't just a prettier version of

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something we already had. Right. This is

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genuinely new science.

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Avery: Absolutely. According to the International

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Centre for Radio Astronomy Research, this

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updated release from the GLEAM X survey

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delivers twice the resolution and ten times

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the sensitivity of earlier efforts. Plus it

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covers twice as much of the sky.

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Anna: What kinds of things can we see in this

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image?

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Avery: Well, Silvia Montovani, a, uh, PhD student

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at Curtin University who led the project,

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explains you can clearly identify remnants of

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exploded stars represented by large red

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circles in the image. The smaller blue

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regions indicate stellar nurseries where new

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stars are actively forming.

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Anna: So it's showing us both the birth and death

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of stars.

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Avery: Exactly. One of the major focuses of this

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survey is finding supernova remnants, which

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are notoriously difficult to spot in the

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cluttered background of the Milky Way.

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Hundreds are already catalogued, but

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astronomers believe thousands more are still

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hidden. With this new level of resolution,

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00:16:45.310 --> 00:16:47.750
those cosmic scars from ancient stellar

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explosions are easier to identify.

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Anna: The image also helps with pulsar studies,

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doesn't it?

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Avery: Yes. Measuring pulsar brightness across

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different radio bands could improve our

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understanding of how these spinning neutron

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stars function and where they live in the

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galaxy. The survey has catalogued over

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98,000 radio sources in total.

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Anna: That's an incredible number. And I read that

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this is setting the stage for an even more

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powerful telescope.

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Avery: Right. The Murchison Wildfield Array will

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eventually be surpassed by the SKA Low Array,

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which is currently under construction in the

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same region of Western Australia. Once the

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SKA observatory is operational, it'll deliver

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even sharper and deeper views of the

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universe.

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Anna: But for now, we have this remarkable

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foundation. Associate Professor Natasha

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Hurley Walker, who leads the GLEAM X survey,

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called this an exciting milestone in

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astronomy, since no low frequency radio

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image of the entire southern galactic plane

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has been published before.

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Avery: And it's not just about the Milky Way. The

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catalogue includes distant galaxies as well.

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So it's a dense, glowing map of our cosmic

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neighbourhood that future generations of

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astronomers will use, refine and expand upon.

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Anna: Well, that wraps up today's episode of

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Astronomy Daily. We covered quite a bit of

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ground today, from the first medical

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evacuation from the ISS to missing dwarf

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galaxies, a, uh, troubled Mars orbiter,

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viruses evolving in space, newly discovered

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00:18:14.040 --> 00:18:16.920
exoplanets, and a spectacular new view of our

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home galaxy.

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Avery: It really shows the incredible breadth of

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space science happening right now. Whether

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it's 300 miles above our heads on the ISS,

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millions of miles away at Mars, or billions

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of light years away in the early universe,

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there's always something new to discover.

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Anna: Thanks so much for joining us today. If you

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00:18:35.200 --> 00:18:37.160
enjoyed the show, please subscribe and leave

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00:18:37.160 --> 00:18:39.360
us a review. It really helps other space

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00:18:39.360 --> 00:18:40.600
enthusiasts find us.

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00:18:41.010 --> 00:18:43.130
Avery: And if you have any questions or topics you'd

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00:18:43.130 --> 00:18:45.130
like us to cover, reach out to us on social

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00:18:45.130 --> 00:18:47.170
media. You'll find us on all the major

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00:18:47.170 --> 00:18:50.050
platforms. Just search for AstroDaily Pod.

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We love hearing from our listeners.

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Anna: Until next time, keep looking up Clear

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skies, Everyone.

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Storeys.